Relationship of Fall Armyworm (Lepidoptera: Noctuidae) from Florida, Honduras, Jamaica, and Mississippi: Susceptibility to Insecticides with Reference to Migration

Abstract

Fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), cultures established in 1985 from larvae collected on corn in Florida and Jamaica and on sorghum in Mississippi and Honduras were tested in the laboratory for susceptibility to carbaryl, permethrin, methomyl, chlorpyrifos, and methyl parathion using leaves from sorghum plants sprayed with insecticide in the field. Methomyl and chlorpyrifos were effective (85% mortality) against 3rd instar FAW larvae from Jamaica and Mississippi whereas mortality of similar larval stages from Honduras was 50%. The Florida culture appeared to be about equally tolerant to all the test insecticides. Carbaryl, methyl parathion and permethrin were ineffective against 3rd instar larvae from all test areas. However, preliminary field tests indicated that 1st instar Honduras FAW larvae are susceptible to methyl parathion. Also, materials shown to be ineffective against 3rd instar larvae in the whorl were effective on FAW when applied to the sorghum seed head in a separate study. Susceptibility responses to insecticides indicate that the FAW population from Mississippi was more similar to test populations from Jamaica and Honduras, than to the test population from Florida, suggesting that the FAW source from Florida may not be the source of insects invading Mississippi.